fix(opencode): retry xAI capacity stream errors (#43640)

Co-authored-by: rekram1-node <rekram1-node@users.noreply.github.com>

packages/opencode/test/provider/error.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, test } from "bun:test"
+import { ProviderError } from "@/provider/error"
+
+describe("provider stream errors", () => {
+  test("retries provider stream errors without a code", () => {
+    const messages = [
+      "The model is currently at capacity due to high demand. Please try again in a few minutes, or use a higher service tier for priority processing: https://docs.x.ai/developers/advanced-api-usage/priority-processing",
+      "The model is temporarily unavailable.",
+    ]
+
+    for (const message of messages)
+      expect(
+        ProviderError.parseStreamError({
+          type: "error",
+          error: { message },
+        }),
+      ).toEqual({
+        type: "api_error",
+        message,
+        isRetryable: true,
+        responseBody: JSON.stringify({ type: "error", error: { message } }),
+      })
+  })
+})